The present invention relates to a material and a method for making an electroconductive pattern.
For the fabrication of flexible LC displays, electrolumin-escent devices and photovoltaic cells transparent ITO (indium-tin oxide) electrodes are used. These electrodes are made by vacuum sputtering of ITO onto a substrate. This method involves high temperatures, up to 250xc2x0 C., and therefore glass substrates are generally used. The range of potential applications is limited, because of the high fabrication costs, the low flexibility (pliability) and stretchability as a consequence of the brittleness of the ITO layer and the glass substrate. Therefore the interest is growing in all-organic devices, comprising plastic resins as a substrate and organic electroconductive polymer layers as electrodes. Such plastic electronics allow the realization of low cost devices with new properties (Physics World, March 1999, p.25-39). Flexible plastic substrates can be provided with an electroconductive polymer layer by continuous roller coating methods (compared to batch process such as sputtering) and the resulting organic electrodes enable the fabrication of electronic devices characterised by a higher flexibility and a lower weight.
The production and the use of electroconductive polymers such as polypyrrole, polyaniline, polyacetylene, polyparaphenylene, polythiophene, polyphenylenevinylene, polythienylenevinylene and polyphenylenesulphide are known in the art.
EP-A 440 957 discloses dispersions of polythiophenes, constructed from structural units of formula (I): 
in which R1 and R2 independently of one another represent hydrogen or a C1-4-alkyl group or together form an optionally substituted C1-4-alkylene residue, in the presence of polyanions. Furthermore, EP-A-686 662 discloses mixtures of A) neutral polythiophenes with the repeating structural unit of formula (I), 
in which R1 and R2 independently of one another represent hydrogen or a C1-C4 alkyl group or together represent an optionally substituted C1-C4 alkylene residue, preferably an optionally with alkyl group substituted methylene, an optionally with C1-C12-alkyl or phenyl group substituted 1,2-ethylene residue or a 1,2-cyclohexene residue, and B) a di- or polyhydroxy- and/or carboxy groups or amide or lactam group containing organic compound; and conductive coatings therefrom which are tempered at elevated temperature, preferably between 100 and 250xc2x0 C., during preferably 1 to 90 seconds to increase their resistance preferably to  less than 300 ohm/square.
EP-A 614 123 discloses a water-soluble electrically conductive composition of matter comprising a polyacid and a polymer comprising at least one conjugated region composed of repeating units which contain a conjugated basic atom. However, as water-soluble electrically conductive polymer comprising at least one conjugated region composed of repeating units which contain a conjugated basic atom, only polyaniline and substituted polyanilines are exemplified.
EP-A 382 046 discloses an electrically conductive resist material, essentially comprising at least one ionic radiation-sensitive polymer and a soluble electrically conductive oligomer or a soluble electrically conductive polymer. Polymers of substituted thiophenes are exemplified, but no specific ionic radiation-sensitive polymers.
EP-A 338 786 discloses a negative working, photosensitive, overlay color proofing film which comprises, in order: (i) a transparent substrate; (ii) a photosensitive layer on the substrate, which photosensitive layer comprises a light sensitive, negative working, polymeric diazonium compound which is the polycondensation product of 3-methoxy-4-diazodiphenylamine sulfate and 4,4xe2x80x2-bis-methoxymethyl diphenyl ether precipitated as the chloride salt, which diazonium compound is present in sufficient amount to photosensitize the layer; and a water insoluble, water swellable binder resin in sufficient amount to bind the layer components in a uniform film; and at least one colorant in sufficient amount to uniformly color the layer; wherein upon imagewise exposure of the photosensitive layer to sufficient actinic radiation the film is capable of being developed with water alone.
Coated layers of organic electroconductive polymers can be structured into patterns using known microlithography techniques. In WO-A-97 18944 a process is described wherein a positive or negative photoresist is applied on top of a coated layer of an organic electroconductive polymer, and after the steps of selectively exposing the photoresist to UV light, developing the photoresist, etching the electroconductive polymer layer and finally stripping the non-developed photoresist with an organic solvent, a patterned layer is obtained. A similar technique has been described in 1988 in Synthetic Metals, volume 22, pages 265-271 for the design of an all-organic thin-film transistor. Such methods are cumbersome as they involve many steps and require the use of hazardous chemicals.
It is an aspect of the present invention to provide a material having a outermost layer that can be processed to an electroconductive pattern by a simple, convenient method which involves a low number of steps and which does not require the use of hazardous chemicals.
An electroconductive pattern can be realized with the materials of the present invention, which are optionally conductivity enhanced, by pattern-wise exposure, with or without a subsequent single wet processing step, and optional conductivity enhancement. No etching liquids or organic solvents are required.
The aspects of the present invention are realized by a material for making an electroconductive pattern, the material comprising a support and a light-exposure differentiable element, characterized in that the light-exposure differentiable element comprises an outermost layer containing a polyanion and a polymer or copolymer of a substituted or unsubstituted thiophene, and optionally a second layer contiguous with the outermost layer; and wherein the outermost layer and/or the optional second layer contains a light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer.
These objects are also realized by a method of making an electroconductive pattern on a support comprising the steps of:
providing a material as disclosed above;
image-wise exposing the material thereby obtaining a differentiation of the removability, optionally with a developer, of the exposed and the non-exposed areas of the outermost layer;
processing the material, optionally with the developer, thereby removing areas of the outermost layer; and
optionally treating the material to increase the electroconductivity of the non-removed areas of the outermost layer.
These objects are also realized by a method of making an electroconductive pattern on a support without a removal step comprising the steps of:
providing a material for making an electroconductive pattern, said material comprising a support and a light-exposure differentiable element, characterized in that said light-exposure differentiable element comprises an outermost layer containing a polyanion and a polymer or copolymer of a substituted or unsubstituted thiophene having a surface resistivity lower than 106 xcexa9/square, and optionally a second layer contiguous with the outermost layer; and wherein the outermost layer and/or said optional second layer contains a bis(aryl diazosulfonate) compound according to formula (I):
MO3Sxe2x80x94Nxe2x95x90Nxe2x80x94Arxe2x80x94Lxe2x80x94Arxe2x80x94Nxe2x95x90Nxe2x80x94SO3Mxe2x80x83xe2x80x83(I)
where Ar is a substituted or unsubstituted aryl group, L is a divalent linking group, and M is a cation; capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer; and
image-wise exposing the material thereby obtaining reduction in the conductivity of the exposed areas relative to non-exposed areas, optionally with a developer.
Further advantages and embodiments of the present invention will become apparent from the following description.
The term xe2x80x9csupportxe2x80x9d means a xe2x80x9cself-supporting materialxe2x80x9d so as to distinguish it from a xe2x80x9clayerxe2x80x9d which may be coated on a support, but which is itself not self-supporting. It also includes any treatment necessary for, or layer applied to aid, adhesion to the light-exposure differentiable element.
The term electroconductive means having a surface resistivity below 106 xcexa9/square. Antistatic materials have surface resistivities in the range from 106 to 1011 xcexa9/square and cannot be used as an electrode.
The term electroconductive pattern means a pattern made up by the non-removed areas of the outermost layer, according to the present invention, which are electroconductive or can be made electroconductive by post-treatment.
Conductivity enhancement refers to a process in which the conductivity is enhanced e.g. by contact with high boiling point liquids such as di- or polyhydroxy- and/or carboxy groups or amide or lactam group containing organic compound optionally followed by heating at elevated temperature, preferably between 100 and 250xc2x0 C., during preferably 1 to 90 seconds, results in conductivity increase. Alternatively in the case of aprotic compounds with a dielectric constant xe2x89xa715, e.g. N-methyl-pyrrolidinone, temperatures below 100xc2x0 C. can be used. Such conductivity enhancement is observed with polythiophenes and can take place during the preparation of the outermost layer or subsequently. Particularly preferred liquids for such treatment are N-methyl-pyrrolidinone and diethylene glycol such as disclosed in EP-A 686 662 and EP-A 1 003 179.
The term removability as used in the description and claims of the present invention means mechanically removable in the absence of a liquid or removable with the application of a liquid with or without the simultaneous or subsequent use of rubbing or other mechanical removal means. The application of liquid can dissolve, swell or disperse the outermost layer according to the present invention such that removal is realized or enabled.
The term light-exposure differentiable element means an element which upon light exposure produces changes in the properties or composition of the exposed parts of the element with respect to the properties or composition of the unexposed parts of the element.
The term multidiazonium salt includes all compounds with at least two groups with two nitrogen atoms bonded together with a double or triple bond, such groups including xe2x80x94Nxe2x89xa1N+ and xe2x80x94Nxe2x95x90Nxe2x80x94R groups e.g. xe2x80x94Nxe2x95x90Nxe2x80x94SO3M groups.
The term resin comprising a diazonium salt means a resin with groups with two nitrogen atoms bonded together with a double or triple bond, such groups including xe2x80x94Nxe2x89xa1N+ and xe2x80x94Nxe2x95x90Nxe2x80x94R groups e.g. xe2x80x94Nxe2x95x90Nxe2x80x94SO3M groups.
In the case of removal of parts (areas) of the outermost layer after pattern-wise exposure, the term surface resistivity ratio means the ratio of the surface resistivity of the parts (areas) of the light-exposure differentiable element from which parts (areas) of the outermost layer, according to the invention, have been removed to that of the parts (areas) of the light-exposure differentiable element from which no parts (areas) of the outermost layer, according to the invention, have been removed, after treatment to enhance the conductivity of the non-removed parts (areas) of the outermost layer if this is required to increase (enhance) the conductivity of the non-removed parts (areas) of the outermost layer.
In the case of non-removal of parts (areas) of the outermost layer after pattern-wise exposure, the term surface resistivity ratio means the ratio of the surface resistivity of the exposed parts (areas) of the outermost layer to that of the non-exposed parts (areas) of the outermost layer.
The material for making an electroconductive pattern, according to the present invention, need not itself be electroconductive as long as patterns produced with such a material can be rendered electroconductive by a post-treatment process, such as a conductivity enhancement process. Furthermore, no material need be removed from the outermost layer containing a polymer or copolymer of a substituted or unsubstituted thiophene, according to the present invention, in order to realize an electroconductive pattern, after optional processing to remove the residual light-sensitive component, as long as differential removability subsequent to exposure is feasible. In this case the light-sensitive component present is capable upon exposure of realizing this effect as well as changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer. The optional second layer must be between the outermost layer and the support as it cannot be the outermost layer.
The term xe2x80x9celectroconductivexe2x80x9d is related to the electric resistivity of the material. The electric resistivity of a layer is generally expressed in terms of surface resistivity Rs (unit xcexa9; often specified as xcexa9/square). Alternatively, the electroconductivity may be expressed in terms of volume resistivity Rv=Rsxc2x7d, wherein d is the thickness of the layer, volume conductivity kv=1/Rv [unit: S(iemens)/cm] or surface conductivity ks=1/Rs [unit: S(iemens).square].
All values of electric resistivity presented herein are measured according to one of the following methods. In the first method the support coated with the electroconductive outermost layer is cut to obtain a strip having a length of 27.5 cm and a width of 35 mm and strip electrodes are applied over its width at a distance of 10 cm perpendicular to the edge of the strip. The electrodes are made of an electroconductive polymer, ECCOCOAT CC-2 available from Emerson and Cumming Speciality polymers. Over the electrode a constant potential is applied and the current flowing through the circuit is measured on a pico-amperometer KEITHLEY 485. From the potential and the current, taking into account the geometry of the area between the electrodes, the surface resistivity in xcexa9/square is calculated.
In the second method, the surface resistivity was measured by contacting the outermost layer with parallel copper electrodes each 35 mm long and 35 mm apart capable of forming line contacts, the electrodes being separated by a teflon insulator. This enables a direct measurement of the surface resistivity.
Supports for use according to the present invention include polymeric films, silicon, ceramics, oxides, glass, polymeric film reinforced glass, glass/plastic laminates, metal/plastic laminates, paper and laminated paper, optionally treated, provided with a subbing layer or other adhesion promoting means to aid adhesion to the light-exposure differentiable element. Suitable polymeric films are poly(ethylene terephthalate), poly(ethylene naphthalate), polystyrene, polyethersulphone, polycarbonate, polyacrylate, polyamide, polyimides, cellulosetriacetate, polyolefins and polyvinylchloride, optionally treated by corona discharge or glow discharge or provided with a subbing layer.
In the case of the realization of an electroconductive pattern via removal of exposed or non-exposed areas such treatment or subbing layer should not hinder complete removal, whereas if the electroconductive pattern can be realized without removal of exposed or non-exposed areas such treatment should make removal of non-exposed or exposed areas more difficult.
In a first embodiment of the material according to the present invention the support is treated with a corona discharge or a glow discharge. Both corona discharge and glow discharge enable the use of polymeric films as a support without a subbing layer. Such materials can be developed, optionally while softly rubbing, and still yield an excellent conductivity ratio between exposed and non-exposed areas.
A light-exposure differentiable element, according to the present invention, is an element which upon light exposure produces changes in the properties or composition of the exposed parts of the element with respect to the properties or composition of the unexposed parts of the element. Examples of such changes are exposure-induced crosslinking; exposure-induced increase or decrease of solubility; and exposure-induced increase or decrease of adhesion to the support.
According to the present invention, these changes in the properties or composition of the light-exposure differentiable element are due to the presence of a light-sensitive component in the outermost layer and/or the second layer, which enables either the exposed or unexposed parts of the outermost layer to be removed, optionally with the assistance of a developer, i.e. the removability can either be rendered more (positive working) or less (negative working) removable by a developer upon exposure to light.
In a second embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is a multidiazonium salt or a resin comprising a diazonium salt, which reduces the removability of exposed parts of the outermost layer. Combinations of resins comprising a diazonium salt can also be used. If the light-sensitive component is a multidiazonium salt or a resin comprising a diazonium salt, increasing the pH of the coating dispersions and solutions used in preparing the light-exposure differentiable element has been found to improve the shelf-life, i.e. retention of properties upon storage, of materials according to the present invention. pH""s between 2.5 and 9 are preferred, with pH""s between 3 and 6 being particularly preferred. Such pH""s can, for example, be realized by adding ammonium hydroxide.
In a third embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is a quinone diazide compound, which increases the removability of exposed parts of the outermost layer.
In a fourth embodiment of the material according to the present invention the outermost layer has a surface resistivity lower than 106 xcexa9/square.
In a fifth embodiment of the material according to the present invention the outermost layer has a surface resistivity lower than 104 xcexa9/square.
In a sixth embodiment of the material according to the present invention the outermost layer has a surface resistivity capable of being lower than 106 xcexa9/square after treatment in a so-called conductivity enhancement process.
Polymer or copolymer of a substituted or unsubstituted thiophene
In a seventh embodiment of the material according to the present invention the polymer of a substituted or unsubstituted thiophene corresponds to the formula (II): 
in which n is larger than 1 and each of R1 and R2 independently represents hydrogen or an optionally substituted C1-4 alkyl group or together represent an optionally substituted C1-4 alkylene group or an optionally substituted cycloalkylene group, preferably an ethylene group, an optionally alkyl-substituted methylene group, an optionally C1-12 alkyl- or phenyl-substituted ethylene group, a 1,3-propylene group or a 1,2-cyclohexylene group.
The preparation of such a polythiophene and of aqueous dispersions containing such a polythiophene and a polyanion is described in EP-A-440 957 and corresponding U.S. Pat. No. 5,300,575. Basically the preparation of polythiophene proceeds in the presence of polymeric polyanion compounds by oxidative polymerisation of 3,4-dialkoxythiophenes or 3,4-alkylenedioxythiophenes according to the following formula: 
wherein R1 and R2 are as defined above.
Stable aqueous polythiophene dispersions having a solids content of 0.05 to 55% by weight and preferably of 0.1 to 10% by weight can be obtained by dissolving thiophenes corresponding to the formula above, a polyacid and an oxidising agent in an organic solvent or preferably in water, optionally containing a certain amount of organic solvent, and then stirring the resulting solution or emulsion at 0xc2x0 C. to 100xc2x0 C. until the polymerisation reaction is completed. The polythiophenes formed by the oxidative polymerisation are positively charged, the location and number of such positive charges being not determinable with certainty and therefore not mentioned in the general formula of the repeating units of the polythiophene polymer.
The oxidising agents are those which are typically used for the oxidative polymerisation of pyrrole as described in for example J. Am. Soc. 85, 454 (1963). Preferred inexpensive and easy-to-handle oxidising agents are iron(III) salts, e.g. FeCl3, Fe(ClO4)3 and the iron(III) salts of organic acids and inorganic acids containing organic residues. Other suitable oxidising agents are H2O2, K2Cr2O7, alkali or ammonium persulphates, alkali perborates, potassium permanganate and copper salts such as copper tetrafluoroborate. Air or oxygen can also be used as oxidising agents. Theoretically, 2.25 equivalents of oxidising agent per mol of thiophene are required for the oxidative polymerisation thereof (J. Polym. Sci. Part A, Polymer Chemistry, Vol. 26, p.1287, 1988). In practice, however, the oxidising agent is used in excess, for example, in excess of 0.1 to 2 equivalents per mol of thiophene.
The polyacid forms a polyanion or, alternatively, the polyanion can be added as a salt of the corresponding polyacids, e.g. an alkali salt. Preferred polyacids or salts thereof are polymeric carboxylic acids such as poly(acrylic acid), poly((meth)acrylic acid) and poly(maleic acid) or polymeric sulphonic acids such as poly(styrene sulphonic acid) or poly(vinyl sulphonic acid). Alternatively, copolymers of such carboxylic and/or sulphonic acids and of other polymerizable monomers such as styrene or acrylates can be used.
In an eighth embodiment of the material according to the present invention the polyanion is poly(styrene sulphonate).
The molecular weight of these polyanion forming polyacids is preferably between 1000 and 2xc3x97106, more preferably between 2000 and 5xc3x97105. These polyacids or their alkali salts are commercially available and can be prepared according to the known methods, e.g. as described in Houben-Weyl, Methoden der Organische Chemie, Bd. E20 Makromolekulare Stoffe, Teil 2, (1987), pp. 1141.
The coating dispersion or solution of a polyanion and a polymer or copolymer of a substituted or unsubstituted thiophene can also comprise additional ingredients, such as one or more binders, one or more surfactants, spacing particles, UV-acutance compounds or IR-absorbers.
Anionic and non-ionic surfactants are preferred. Suitable surfactants include ZONYL(trademark) FSN 100 and ZONYL(trademark) FSO 100, an ethoxylated non-ionic fluoro-surfactant with the structure: F(CF2CF2)yCH2CH2O(CH2CH2O)xH, where x=0 to ca. 15 and y=1 to ca. 7, both from Du Pont.
The coating dispersion or solution of a polyanion and a polymer or copolymer of a substituted or unsubstituted thiophene preferably also comprises an organic compound that is: a linear, branched or cyclic aliphatic C2-20 hydrocarbon or an optionally substituted aromatic C6-14 hydrocarbon or a pyran or a furan, the organic compound comprising at least two hydroxy groups or at least one xe2x80x94COX or xe2x80x94CONYZ group wherein X denotes xe2x80x94OH and Y and Z independently of one another represent H or alkyl; or a heterocyclic compound containing at least one lactam group. Examples of such organic compounds are e.g. N-methyl-2-pyrrolidinone, 2-pyrrolidinone, 1,3-dimethyl-2-imidazolidone, N,N,Nxe2x80x2,Nxe2x80x2-tetramethylurea, formamide, dimethylformamide, and N,N-dimethylacetamide. Preferred examples are sugar or sugar derivatives such as arabinose, saccharose, glucose, fructose and lactose, or di- or polyalcohols such as sorbitol, xylitol, mannitol, mannose, galactose, sorbose, gluconic acid, ethylene glycol, di- or tri(ethylene glycol), 1,1,1-trimethylol-propane, 1,3-propanediol, 1,5-pentanediol, 1,2,3-propantriol, 1,2,4-butantriol, 1,2,6-hexantriol, or aromatic di- or polyalcohols such as resorcinol.
A multidiazonium salt is a salt with at least two groups with two nitrogen atoms bonded together with a double or triple bond, such groups including xe2x80x94Nxe2x89xa1N+ and xe2x80x94Nxe2x95x90Nxe2x80x94R groups, e.g. xe2x80x94Nxe2x95x90Nxe2x80x94SO3M groups e.g. bisdiazonium salts, trisdiazonium salts, tetrakisdiazonium salts, bis(aryldiazosulphonate) salts, tris(aryldiazosulphonate) salt and terakis(bis(aryldiazosulphonate) salts.
Upon exposure the light-exposure differentiable element containing a multidiazonium salt is converted from water removable to water unremovable (due to the destruction of the diazonium groups) and additionally the photolysis products of the diazo may increase the level of crosslinking of the polymeric binder or resin comprising a multidiazonium salt if present, thereby selectively converting the surface, into an image pattern, from removable to unremovable. The unexposed areas remain unchanged, i.e. removable. Combinations of multidiazonium salts can also be used.
Bisdiazonium salts for use in the present invention include: benzidine tetrazoniumchloride, 3,3xe2x80x2-dimethylbenzidine tetrazoniumchloride, 3,3xe2x80x2-dimethoxybenzidine tetrazoniumchloride, 4,4xe2x80x2-diaminodiphenylamine tetrazoniumchloride, 3,3xe2x80x2-diethylbenzidine tetrazoniumsulphate, 4-aminodiphenylamine diazoniumsulphate, 4-aminodiphenylamine diazoniumchloride, 4-piperidino aniline diazoniumsulphate, 4-diethylamino aniline diazoniumsulphate and oligomeric condensation products of diazodiphenylamine and formaldehyde.
In a ninth embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is a bis(aryldiazosulphonate) salt, a tris(aryldiazosulphonate) salt or a tetrakis(aryldiazosulphonate) salt, which reduces the removability of exposed parts of the outermost layer.
In an tenth embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is a bis(aryldiazosulphonate) salt, which reduces the removability of exposed parts of the outermost layer, according to formula (I):
MO3Sxe2x80x94Nxe2x95x90Nxe2x80x94Arxe2x80x94Lxe2x80x94Arxe2x80x94Nxe2x95x90Nxe2x80x94SO3Mxe2x80x83xe2x80x83(I)
where Ar is a substituted or unsubstituted aryl group, L is a divalent linking group, and M is a cation. L preferably represents a substituted or unsubstituted divalent aryl group or a substituted or unsubstituted saturated or unsaturated alkylene group, whose chain is optionally substituted with at least one of an oxygen atom, a sulphur atom or a nitrogen atom. Ar preferably represents an unsubstituted phenyl group or a phenyl group substituted with one or more alkyl groups, aryl groups, alkoxy groups, aryloxy groups or amino groups. M preferably represents a cation such as NH4+ or a metal ion such as a cation of Al, Cu, Zn, an alkaline earth metal or alkali metal.
Particularly suitable bis(aryldiazosulphonate) salts, according to the present invention, are:
In an eleventh embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is a bis(aryldiazosulphonate) salt, which reduces the removability of exposed parts of the outermost layer, is selected from the group consisting of BADS01, BADS02 and BADS03.
In a first embodiment of the method of making an electroconductive pattern on a support without a removal step, according to the present invention, the aryldiazosulfonate according to formula (I) is selected from the group consisting of BADS01, BADS02 and BADS03.
The term resin comprising a diazonium salt means a resin with groups with two nitrogen atoms bonded together with a double or triple bond, such groups including xe2x80x94Nxe2x89xa1N+ and xe2x80x94Nxe2x95x90Nxe2x80x94R groups e.g. xe2x80x94Nxe2x95x90Nxe2x80x94SO3M groups. Suitable resins comprising a diazonium salt, according to the present invention, include polymers or copolymers of an aryldiazosulphonate and condensation products of an aromatic diazonium salt. Such condensation products are described, for example, in DE-P-1 214 086.
Upon exposure the light-exposure differentiable element containing resins comprising a diazonium salt are converted from removable to unremovable (due to the destruction of the diazonium groups) and additionally the photolysis products of the diazo may increase the level of crosslinking of the polymeric binder or resin comprising a diazonium salt, thereby selectively converting the surface, into an image pattern, from removable to unremovable. The unexposed areas remain unchanged, i.e. removable.
In a twelfth embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is a polymer or copolymer of an aryldiazosulphonate, which reduces the removability of exposed parts of the outermost layer.
In a thirteenth embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is a polymer or copolymer of an aryldiazosulphonate, which reduces the removability of exposed parts of the outermost layer, represented by formula (III): 
wherein R0, R1 and R2 each independently represent hydrogen, an alkyl group, a nitrile or a halogen, e.g. Cl, L represents a divalent linking group, n represents 0 or 1, A represents an aryl group and M represents a cation. L preferably represents divalent linking group selected from the group consisting of: xe2x80x94(X)txe2x80x94CONR3xe2x80x94, xe2x80x94(X)txe2x80x94COOxe2x80x94, xe2x80x94Xxe2x80x94 and xe2x80x94(X)txe2x80x94COxe2x80x94, wherein t represents 0 or 1; R3 represents hydrogen, an alkyl group or an aryl group; X represents an alkylene group, an arylene group, an alkylenoxy group, an arylenoxy group, an alkylenethio group, an arylenethio group, an alkylenamino group, an arylenamino group, oxygen, sulphur or an aminogroup. A preferably represents an unsubstituted aryl group, e.g. an unsubstituted phenyl group or an aryl group, e.g. phenyl, substituted with one or more alkyl groups, aryl groups, alkoxy groups, aryloxy groups or amino groups. M preferably represents a cation such as NH4+ or a metal ion such as a cation of Al, Cu, Zn, an alkaline earth metal or alkali metal.
Polymers and copolymers of an aryldiazosulphonate can be prepared by homo- or copolymerization of aryldiazosulphonate monomers with other aryldiazosulphonate monomers and/or with vinyl monomers such as (meth)acrylic acid or esters thereof, (meth)acrylamide, acrylonitrile, vinylacetate, vinylchloride, vinylidene chloride, styrene, alpha-methyl styrene etc. A particularly preferred comonomer is hydroxyethylmethacrylate. Suitable aryldiazosulphonate monomers for preparing such polymers and copolymers of an aryldiazosulphonate, as used in the present invention, are:
Specific examples of suitable aryldiazosulphonate polymers are described in EP-A-771 645.
Suitable resins comprising a diazonium salt, according to the present invention, are given below. In the case of polymers and copolymers of an aryldiazosulphonate, the respective monomer ratios are expressed as percentages by weight.
In a fourteenth embodiment of the material according to the present invention in the light-exposure differentiable element the weight ratio of the polymer or copolymer of an aryldiazosulphonate to the polymer or copolymer of a substituted or unsubstituted thiophene is between 10:200 and 400:200.
In a fifteenth embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is a combination of a resin comprising an aryldiazosulphonate, which reduces the removability of exposed parts of the outermost layer, and a bis(aryldiazosulphonate) salt, which reduces the removability of exposed parts of the outermost layer.
In a sixteenth embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is a combination of a resin comprising an aryldiazosulphonate, which reduces the removability of exposed parts of the outermost layer, and a bis(aryldiazosulphonate) salt, which reduces the removability of exposed parts of the outermost layer, in the weight percentage ratio range of 60%/40% to 10%/90%.
In a seventeenth embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is a combination of a resin comprising an aryldiazosulphonate, which reduces the removability of exposed parts of the outermost layer, and a bis(aryldiazosulphonate) salt, which reduces the removability of exposed parts of the outermost layer, in the weight percentage ratio range of 50%/50% to 20%/80%.
In an eighteenth embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is a combination of a copolymer of hydroxyethylmethacrylate and sodium-4-methacryloyl-aminophenyl-diazo-sulphonate, which reduces the removability of exposed parts of the outermost layer, and an bis(aryldiazosulphonate) salt, which reduces the removability of exposed parts of the outermost layer.
In a nineteenth embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is a quinonediazide compound, which increases the removability of exposed parts of the outermost layer.
In a twentieth embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is an o-quinone-diazide compound (NQD), which increases the removability of exposed parts of the outermost layer.
Particularly preferred o-quinone-diazide compounds are o-naphthoquinonediazidosulphonic acid esters or o-naphthoquinone diazidocarboxylic acid esters of various hydroxyl compounds and o-naphthoquinonediazidosulphonic acid amides or o-naphthoquinonediazidocarboxylic acid amides of various aromatic amine compounds.
Two variants of NQD systems can be used: one-component systems and two-component systems. In the former case, the sulphonic or carboxyl acid group is linked directly to the phenolic hydroxy group of a water insoluble, alkali soluble or swellable resin having a phenolic hydroxy group. It is preferred that some phenolic hydroxy groups remain unsubstituted. Examples of such compounds include phenol, cresol, resorcinol and pyrogallol. Examples of preferred water insoluble, alkali soluble or swellable resins having a phenolic hydroxy group include phenol-formaldehyde resin, cresol-formaldehyde resin, pyrogallol-acetone resin and resorcinol-benzaldehyde resin. Typical examples include esters of napthoquinone-(1,2)-diazidosulphonic acid and phenol-formaldehyde resin or cresol-formaldehyde resin, esters of naphthoquinone-(1,2)-diazido-(2)-5-sulphonic acid and pyrogallol-acetone resin as disclosed in U.S. Pat. No. 3,635,709 and esters of naphthoquinone-(1,2)-diazido-(2)-5-sulphonic acid and resorcinol-pyrogallol-acetone copolycondensates as disclosed in JP KOKAI No. Sho 55-76346.
Examples of other useful compounds are polyesters having hydroxyl groups at their termini esterified with o-naphthoquinonediazidesulphonyl chloride as disclosed in JP KOKAI No. Sho 50-117503; homopolymers of p-hydroxystyrene or copolymers thereof with other copolymerizable monomers esterified with o-naphthoquinonediazidosulphonyl chloride as disclosed in JP KOKAI No. Sho 50-113305; condensates of alkyl acrylate-acryloyloxyalkyl carbonate-hydroxyalkyl acrylate copolymers with o-naphthoquinonediazidosulphonyl chloride as disclosed in U.S. Pat. No. 3,859,099; amides of copolymers of p-aminostyrene and monomers copolymerizable therewith and o-naphthoquinonediazido-sulphonic acid or o-naphthoquinonediazidocarboxylic acid as disclosed in U.S. Pat. No. 3,759,711; as well as ester compounds of polyhydroxybenzophenone and o-naphthoquinonediazidosulphonyl chloride.
In a twenty-first embodiment of the material according to the present invention the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is an o-quinone-diazide compound (PQD), which increases the removability of exposed parts of the outermost layer, and the light-exposure differentiable element further contains an alkali soluble resin.
Particularly suitable quinonediazide compounds according to the present invention are:
In the materials for making an electroconductive pattern, according to the present invention, the light-exposure differentiable element contains a binder.
In a twenty-second embodiment of the material according to the present invention the outermost layer contains a binder, e.g. polyvinyl alcohol and a vinylidene chloride, methyl methacrylate, itaconic acid (88/10/2) terpolymer, if the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is present in the outermost layer.
In a twenty-third embodiment of the material according to the present invention the optional second layer contains a binder, e.g. polyvinyl alcohol and a hydroxyethyl methacrylate copolymer, if the light-sensitive component capable upon exposure of changing the removability of the exposed parts of the outermost layer relative to the unexposed parts of the outermost layer is present in the second layer.
Suitable binders for use in the present invention are described in EP-A 564 911 and include water-soluble polymers, such as poly(vinyl alcohol), water-soluble homo- and co-polymers of acrylic acid and homo- and co-polymers of methacrylic acid, and polymer latexes. Preferred binders include poly(vinyl alcohol) and homo- and co-polymers of hydroxyethyl methacrylate and copolymers of 2-propenoic acid 2-phosphonooxy)ethyl ester, copolymers of 2-methyl-2-propenoic acid 2-phosphonooxy)ethyl ester. Such binders may be treated with a hardening agent, e.g. an epoxysilane such as 3-glycidyloxypropyltrimethoxysilane as described in EP-A 564 911, which is especially suitable when coating on a glass substrate.
In the application of NQD as two-component systems various low-molecular NQD sulphonic or carboxyl acid derivatives are dissolved mainly in certain water insoluble, alkali soluble or swellable resins; the latter acts as polymeric binder for NQD. Preferably the 4- or 5-sulphonyl or carboxyl substituted 1,2 naphthoquinonediazides are esters of 1,2 naphthoquinonediazides-4- or -5-sulphonic or carboxylic acids with a phenolic compound having at least two phenolic hydroxy groups, more preferably with a phenolic compound having at least three phenolic hydroxy groups. Further suitable 1,2 naphthoquinone-2-diazides are disclosed in GB-A 739654 and in U.S. Pat. No. 4,266,001. Preferred water insoluble, alkali soluble or swellable resins are resins, which comprise phenolic hydroxy groups, oxime groups or sulphonamido groups. More preferred are resins having phenolic hydroxy groups, and phenolic hydroxy functionalized derivatives of poly(meth)acrylates, which can be synthesised starting from e.g. hydroxyethyl(meth)acrylate. Most preferred are synthetic novolac resins and typical examples thereof are phenolformaldehyde resin, cresol-formaldehyde resin, and phenol-cresol-formaldehyde copolycondensed resins as disclosed in JP KOKAI No. Sho 55-57841.
The material of the present invention can be image-wise exposed to ultraviolet light optionally in combination with blue light in the wavelength range of 250 to 500 nm or infrared light. Upon image-wise exposure, a differentiation of the removability with a developer of the exposed and non-exposed areas is induced. Useful exposure sources are high or medium pressure halogen mercury vapour lamps, e.g. of 1000 W or lasers having an emission wavelength in the range from about 700 to about 1500 nm, such as a semiconductor laser diode, a Nd:YAG laser or a Nd:YLF laser.
After the image-wise exposure the material is developed in a developer which can be deionized water or is preferably water-based. During development the exposed (positive working) or non-exposed (negative working) areas together with the electroconductive polymer are removed and an electroconductive pattern is thereby obtained. Suitable aqueous developers are deionized water, AZ303 (Clariant) or EN232 (AGFA-GEVAERT N.V.). When a subbing layer (also called substrate layer) is present on the support the material is preferably rubbed thoroughly with a tissue during development to avoid residual conductivity. The rubbing can be done in the processing fluid or in a separate water bath after the development stage. Equal results can be obtained by applying a high pressure water jet after the development stage, thereby avoiding contact with the conductive areas. Alternatively, if conductivity enhancement is necessary, the developer can contain the conductivity enhancement agent, thereby combining the steps of development and contact with the conductivity enhancement agent.
While the present invention will hereinafter be described in connection with preferred embodiments thereof, it will be understood that it is not intended to limit the invention to those embodiments. All percentages given in the EXAMPLES are percentages by weight unless otherwise stated.